1. Dansk Landbrugsrådgivning Landscentret The contribution of biogas plants to nutrient management planning Adviser Torkild Birkmose, DAAS, Denmark Photo: Torben Skøtt, BioPress

2. Dansk Landbrugsrådgivning Landscentret Biogas rests on tree legs Biogas EnergyEnvironmentAgriculture

3. Dansk Landbrugsrådgivning Landscentret Agricultural advantages Improved fertilizer value of nitrogen Balanced P and K-balance in slurry Homogeneous and light fluid Full declaration of nutrients Free from germs and seeds Reduced costs for transportation of slurry

4. Dansk Landbrugsrådgivning Landscentret Environmental advantages Reduced nitrate leaching Reduced odour problems Reduced green house gas emission Controlled recycling of organic waste

5. Dansk Landbrugsrådgivning Landscentret Mixing and digesting slurry change the characteristic of the slurry DM, % N-tot, kg/t NH 4 - N, kg/t P, kg/t K, kg/t pHNH 4 - N, % Digested slurry Pig slurry Cattle slurry 4,8 5,0 7,5 4,4 4,8 3,9 3,5 2,9 2,4 1,0 1,1 0,9 2,3 3,5 7,6 7,1 6,9 81 74 61

6. Dansk Landbrugsrådgivning Landscentret Fertilizer value

7. Dansk Landbrugsrådgivning Landscentret Ammonia evaporation in spring barley 0 10 20 30 40 50 20022003 NH 3 -loss, % of spread NH 4 -N Untreated pig slurryDigested pig slurry

8. Dansk Landbrugsrådgivning Landscentret Improved fertilizer effect of nitrogen - trials in winter wheat 020406080100 Cattle slurry, injected Pig slurry, injected Digested slurry, injected Cattle slurry, trailing hoses Pig slurry, trailing hoses Digested slurry, trailing hoses N-utilization, % (fertilizer equivalent)

9. Dansk Landbrugsrådgivning Landscentret Fertilizer plan for nitrogen for 1 ha grass 250 N-requirement, kg 170 N in slurry, kg total 6040N-utilization, % 10268N- in slurry, utilized, kg 34 17 ---- Saved, kg Saved, £ 148182Mineral fertilizer Digested slurry Cattle slurryPer hectare

10. Dansk Landbrugsrådgivning Landscentret Digestion reduces risk of spreading diseases

11. Dansk Landbrugsrådgivning Landscentret Digested slurry is low on germs <5 1,300,000 140,000 690,000 9,000,000 62,000 Mar. 18 May 13 July 15 Sept. 9 Nov. 11 AfterBeforeDate Test results from Ribe Biogas, bacteria per ml. slurry (1998) Log 10 germs per ml. slurry Time, weeks Slurry tank, 6-8°C Mesofile biogas, 35°C Thermofile biogas, 53°C 10 6 5 3

12. Dansk Landbrugsrådgivning Landscentret Digestion reduces odour

13. Dansk Landbrugsrådgivning Landscentret Reduction of odour compounds in the biogas reactor

14. Dansk Landbrugsrådgivning Landscentret Concentration of VFA in slurry

15. Dansk Landbrugsrådgivning Landscentret Carcass chamber for collecting air samples

16. Dansk Landbrugsrådgivning Landscentret Odour concentration in air samples after spreading